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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        function my_flat(arr,depth){
            if(depth<=0||!Array.isArray(arr)){
                return arr;
            }
            let res = []
            for(let i=0;i<arr.length;i++){
                if(Array.isArray(arr[i])){
                    res = res.concat(my_flat(arr[i],depth-1))
                }
                else{
                    res.push(arr[i])
                }
            }
            return res
        }
        const arr2 = [0, 1, [2, [3, [4, 5]]]];
        console.log(my_flat(arr2,1))
    </script>
</body>
</html>